This avalanche advisory is provided through a partnership between the Tahoe National Forest and the Sierra Avalanche Center. This advisory covers the Central Sierra Nevada Mountains between Yuba Pass on the north and Ebbetts Pass on the south. Click here for a map of the forecast area. This advisory applies only to backcountry areas outside established ski area boundaries. This advisory describes general avalanche conditions and local variations always occur. This advisory expires 24 hours after the posted time unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.


This Avalanche Advisory was published on January 25, 2007:

January 25, 2007 at 1:00 am

Forecast Discussion:

This advisory was posted on Thursday, January 25, 2007 at 3:39 pm

The bottom line: Avalanche danger is LOW for all elevations and aspects.

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A continued mild weather pattern with a slight increase in cloud cover is expected tonight and Friday. A slight cooling trend is expected at the upper elevations tomorrow, but daytime air temperatures should still rise above freezing at the upper elevations. Light to moderate southwest winds are expected to continue through Friday.

An overall stable snowpack exists throughout the forecast area. The snowpack remains dominated by crusts and layers of faceted, sugar like snow. Layer bonding tests continue to show moderate to hard force shear failure at the interface of faceted snow and crust layers on most all snow covered aspects, that hold enough snow for winter recreation. The strength of the existing crusts is keeping the snowpack from failing at this time. Observed failures in layer bonding tests create concern for future snowpack failure in response to additional snow loading. Snow on northerly aspects is remaining cold despite warm air temperatures. Daily melt-freeze conditions continue to occur on the vast majority of sun exposed aspects. Above freezing air temperatures have been observed above 7,000' throughout the forecast area the past two nights. Despite this, the snowpack has refrozen each night due to clear skies that allow radiation of heat from the snowpack and subsequent cooling of the snow surface.

The bottom line: Avalanche danger is LOW for all elevations and aspects.

The next scheduled update to this advisory will occur tomorrow afternoon.

Brandon Schwartz, Avalanche Forecaster

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Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet): 34 deg. F
Max. temperature at Sierra Crest past 24 hours: 45 deg. F
Average wind direction at Sierra Crest past 24 hours: southwesterly
Average wind speed at Sierra Crest past 24 hours: 20 mph
Maximum wind gust at Sierra Crest past 24 hours: 29 mph
New snow fall at 8,200 feet past 24 hours: 0 inches
Total snow depth at 8,200 feet: 35 inches

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Mountain Weather Forecast For Friday:
Partly cloudy skies
Temperature forecast for 8,000 to 9,000 feet: 35 - 40 deg. F
Ridgetop winds forecast for the Sierra Crest: southwesterly 20 - 30 mph
Snowfall expected in the next 24 hours: 0 inches

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2 Day Mountain Weather Forecast:
7000 to 8000 Feet
Tonight, becoming partly cloudy with lows 18 to 28 degrees, F. Southwest winds 18 to 28 mph. Friday, partly cloudy skies with daytime highs around 40 degrees F. Southwest winds at 10 to 15 mph are expected.

Above 8000 Feet
Tonight, becoming partly cloudy with lows 22 to 30 degrees, F. Southwest winds 15 to 25 mph. Friday, partly cloudy skies with daytime highs around 38 degrees F. Southwest winds at 20 to 30 mph are expected.


The bottom line:


Andy Anderson - Avalanche Forecaster, Tahoe National Forest

Weather Observations from along the Sierra Crest between 8200 ft and 8800 ft:

0600 temperature: deg. F.
Max. temperature in the last 24 hours: deg. F.
Average wind direction during the last 24 hours:
Average wind speed during the last 24 hours: mph
Maximum wind gust in the last 24 hours: mph
New snowfall in the last 24 hours: O inches
Total snow depth: inches

Two-Day Mountain Weather Forecast - Produced in partnership with the Reno NWS

For 7000-8000 ft:
  Thursday: Thursday Night: Friday:
Weather:
Temperatures: deg. F. deg. F. deg. F.
Wind direction:
Wind speed:
Expected snowfall: O in. O in. O in.

For 8000-9000 ft:
  Thursday: Thursday Night: Friday:
Weather:
Temperatures: deg. F. deg. F. deg. F.
Wind direction:
Wind speed:
Expected snowfall: O in. O in. O in.